http://articles.philly.com/2011-04-26/news/29474846_1_largest-gas-producing-state-marcellus-shale-coalition-tax-natural-gasExcerpt:
"Of 783 companies that filed corporate net-income tax returns in 2008, the study said, 85 percent paid nothing in taxes. That is because drillers operating as corporations can shift income to tax-haven states, such as Delaware, leaving little or no income on the books in Pennsylvania.
Other drillers, including nine of the top 10 permit holders in the Marcellus Shale, structure their businesses as limited liability companies or limited partnerships. In doing so, they avoid corporate income taxes altogether and instead pay the much lower personal income-tax rate on profits. At least 80 percent of all permit-holding drilling companies are now operated by these L.L.C.s or L.P.s, the study found."